A developing cartridge to be assembled in an electrophotographic type image forming device is well known. The developing cartridge includes a cartridge frame for accommodating therein developing agent (toner), a developing roller rotatably supported to the cartridge frame, and a seal member for restraining leakage of toner out of the cartridge frame.
Japanese Patent Application Publication No. 2011-150269 discloses a developing cartridge provided with seal members including a pair of side seals each positioned between each axial end portion of a developing roller and a developing frame, and a lower film extending over a length of the developing roller and between the developing roller and the developing frame. Each axial end portion of the lower film is in contact with each side seal.
With this structure, each side seal is adapted to restrain toner from leaking through a gap between each axial end portion of the developing roller and the developing frame, and the lower film is adapted to restrain toner from leaking through a gap between the lengthwise portion of the developing roller and the developing frame.